It is known to store rich media files, such as movies, as video files for streaming media playing stored online on disc. While it is convenient to describe the problems resolved by the invention and a preferred embodiment of the invention in relation to the playing of videos, the invention is applicable more widely to any rich media having a large data file, typically accessed sequentially. Different formats (e.g. REAL MEDIA and WINDOWS STREAMING, and QUICK TIME) store videos of movies on disc at commercial Video Farms.
Play devices capable of playing back video of these different formats exist. It is possible to have Video-on-Demand by remotely accessing a Video Farm, and an appropriate magnetic disc, via telecommunications links (e.g. the Internet or World-wide Web). Upon accessing a Video Farm a user's play device negotiates with a control computer at the Video Farm to select the correct video format for the user's play device and to agree on a bit rate (typically 56 kbit/s, or 128 kbit/s, or 256 kbit/s). The Video Farm computer then selects the correct disc memory with the movie stored at the correct bit rate and in the correct format and downloads the movie to the user.
This is expensive in memory. For each movie the memory needs to store multiple copies to cater different formats and bit rates. In the case of three formats and three bit rates this is nine copies. Video Farms typically use high quality fault tolerant magnetic disc arrays which have good reliability but which are expensive per gigabyte (GB) of video stored. It is possible to use cheaper disc drives such as single spindle EIDE disc drives such as may be found in a PC, but they are not fault tolerant and can be a point of failure in the delivery of Video-on-Demand.
It is of course known to store video on tape, but this is not used for the on line provision of video movies because of the long latency time that is inherent with tape: it takes time for a tape library to locate the correct tape, retrieve it and put it into a tape drive, and begin playing the tape. Many customers are not prepared to wait and so Video-on-Demand is provided using disc memory storage at the Video Farm.
It is an aim of at least some aspects of the invention to provide an improved way of delivering rich media. In many embodiments the invention aims to provide a cheaper way of providing rich media than by using fault tolerant disc arrays to store the data.